13CNMR and static magnetic susceptibility inC60…

The static spin susceptibility, ${\ensuremath{\chi}}_{s}^{\mathrm{SQ}}$ and ${\ensuremath{\chi}}_{s}^{\mathrm{NMR}},$ in ${\mathrm{C}}_{60}$ superconductors ${\mathrm{K}}_{3}{\mathrm{C}}_{60}$ and ${\mathrm{Rb}}_{3}{\mathrm{C}}_{60}$ was studied using a dc superconducting quantum interference device magnetometer and ${}^{13}\mathrm{C}$ NMR. We found that ${\ensuremath{\chi}}_{s}^{\mathrm{SQ}}$ has a peculiar temperature (T) dependence behaving as $(1\ensuremath{-}{\mathrm{CT}}^{2})$ with a positive constant $C\ensuremath{\sim}(1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}) {\mathrm{deg}}^{\ensuremath{-}2},$ contrary to the almost T independent ${\ensuremath{\chi}}_{s}^{\mathrm{NMR}}.$ These observations indicate a possibility that there exist Kondo-like impurities, whose Kondo temperature is $\ensuremath{\sim}500 \mathrm{K}$ and whose content is $\ensuremath{\sim}0.001$ spins per carbon. On the basis of these studies, the lattice constant dependence of the intrinsic spin susceptibility was established to be $d{\ensuremath{\chi}}_{s}{/da}_{0}=(5.7\ifmmode\pm\else\textpm\fi{}0.4)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4} {\mathrm{e}\mathrm{m}\mathrm{u}/\mathrm{m}\mathrm{o}\mathrm{l}\mathrm{}\mathrm{C}}_{60}/\mathrm{\AA{}}$ in ${A}_{3}{\mathrm{C}}_{60}$ superconductors where A is an alkali metal.